The present invention relates to an authentication system and an authentication method for authenticating mobile information terminals such as mobile telephones.
Many industrial fields have adopted a bar code system based on bar codes that represent alphanumeric characters describing the types and status of produces on which the codes are written. The bar code system allows the products to be identified in type and status when their codes are read and interpreted.
Most conventional bar codes are known as one-dimensional bar codes each made up of bars (black bar-like portions) of different thicknesses combined with spaces (blanks). Each bar-space combination constitutes a code pattern representative of a code number for product identification and management.
A two-dimensional bar code system has also been proposed. This system is based on two-dimensional codes each made of a plurality of square cells arranged into a two-dimensional code pattern in keeping with predetermined layout rules. Each code pattern represents a unique code number that may be used as an authentication key for authenticating a specific user.
For example, the two-dimensional bar code system may be employed by a firm that organizes a concert. In this case, the firm may distribute two-dimensional codes as authentication keys to users who, having bought their tickets, are allowed to enter the concert hall when submitting their codes. Specifically, the organizing firm assigns a unique code number to each of the users who bought the tickets to the concert. The firm then runs a two-dimensional code generation program that generates two-dimensional codes upon receipt of the assigned code numbers. The two-dimensional codes thus generated are distributed to the users as their authentication keys. After receiving a two-dimensional code, each user presents the code to a receptionist at the concert hall. When the code is authenticated by means of a specific authentication terminal, the user is admitted into the hall.
One disadvantage of the above-mentioned two-dimensional code generation program is that an unscrupulous third party who stole a code number could cause the program to generate an identical two-dimensional code for illegal use. That is because the program cannot help generating the same code when duly presented with a specific code number.
Another disadvantage of the program above is the possibility of impersonation by a third party. An unscrupulous person who got hold of either a medium on which a two-dimensional code is printed or two-dimensional code image data can impersonate the legitimate holder of the code in question.